1. Technical Field
The present disclosure relates generally to a method and apparatus for thermal treatment of tissue and, more particularly, to an apparatus to be used with a conventional endoscope to provide the endoscope with thermal treatment capabilities. The apparatus is particularly contemplated for use with a cystoscope or a urethroscope for hyperthermia treatment of prostatic tissue.
2. Background of the Related Art
Benign prostate hyperplasia (BPH) or hyperplasia affects over one out of every two males over the age of fifty. BPH is the non-cancerous enlargement of the prostate gland and is characterized generally by a constriction of the urethra by the prostate gland. An array of symptoms are associated with BPH including frequent urination, complications in urinary flow and associated pain.
Generally there are two primary methods for treating BPH, namely, drug therapy and surgical intervention. Drug therapy incorporates the use of one or more drugs such as Proscar(trademark) and Hydrin(trademark) to either reduce the size of the prostate or to relax the urethral muscles thereby facilitating the normal functioning of the urinary system. Known drug therapies, however, are limited in their effectiveness and present many drug side effect concerns.
Surgical methods for treating BPH include transurethral resection of the prostate (TURP), transurethral incision of the prostate (TUIP), visual laser assisted prostatectomy (VLAP), balloon dilation and stenting. TURP is the most common method employed for BPH treatment today and involves the insertion of an electrosurgical cutting instrument through the urethral passage. The cutting elements of the instrument are positioned adjacent the prostate gland, and the instrument is energized such that the cutting elements selectively cauterize and resect tissue from the core of the prostate. The TURP procedure, however, has many side effects including bleeding, electrograde ejaculation, impotence, incontinence, edema and a prolonged recovery period for the patient. An example of an electrosurgical cutting instrument utilized in conjunction with a TURP procedure is disclosed in U.S. Pat. No. 5,192,280.
Transurethral incision of the prostate (TUIP) involves the use of an electrocautery device which is passed through the urethra. The device is employed to make multiple incisions in the prostate, thereby permitting the prostate to be displaced from the urethra wall to create an opening for urine flow. Success with the TUIP procedure is generally limited providing only temporary reprocedure in the future.
Visual laser assisted prostatectomy (VLAP) includes insertion of a laser catheter through the urethra and directing laser energy laterally through the catheter sleeve at the urethral wall and the prostatic tissue. The laser energy causes the tissue to coagulate. The coagulated tissue eventually necrosis from lack of blood flow and is naturally removed from the body. Drawbacks of VLAP include increased recovery time, acute pain and irritation, and undesired burning of the urethral wall. Examples of methods and apparatuses utilized in VLAP treatment of BPH are disclosed in U.S. Pat. No. 5,242,438 to Saadatmanesh et al. and U.S. Pat. No. 5,322,507 to Costello.
Balloon dilation and stenting procedures for BPH involve expanding and stretching the enlarged prostate with a balloon catheter to relieve pressure off the constricted urethra while stenting incorporates the insertion of tiny wire-mesh coils which expand into a scaffold to hold the urethra open. Balloon dilation and stenting, however, are only temporary procedures typically requiring follow up within a year period. In addition, stenting presents complications of stent migration and consequent irritation.
Transurethral microwave therapy (TUMT) and high intensity focused ultrasound (HIFU) have been developed for the treatment of BPH. In accordance with a TUMT procedure, a foley-type urethral catheter having a microwave emitting antenna at a probe end is inserted into the urethral passage for a period of time sufficient to treat the tissue by microwave radiation. Intraurethral applicators of this type are described in U.S. Pat. Nos. 4,967,765, 5,234,004 and 5,326,343. The drawbacks of TUMT include the inability to focus the heat energy in the prostatic area and the inability to achieve high temperatures uniformly within the prostate.
High intensity focused ultrasound (HIFU) includes directing high intensity ultrasound waves at the prostate tissue to create heat in a precise area to coagulate and necrose tissue. A transurethral probe is utilized to create the ultrasound beams for both imaging and ablation of the prostatic tissue. Disadvantages of this procedure include the inability to directly focus the ultrasound energy at the prostatic tissue.
A more recent form of treatment for BPH involves thermally treating prostatic tissue with radio frequency electromagnetic energy. For example, one current technique, known as transurethral needle ablation (TUNA(trademark)), involves the transurethral application of a medical instrument having a built-in RF needle electrode system. The TUNA(trademark) instrument is inserted into the urethra and advanced to a position adjacent the prostate. Thereafter, the RF needles are advanced to penetrate the urethral wall and access the prostatic tissue. The RF system is activated whereby a RF current is transmitted through each electrode to pass through the tissue to a grounding pad thereby forming a necrotic legion which is eventually absorbed by the body. Apparatuses and methods for treating BPH via the TUNAS technique are disclosed in U.S. Pat. Nos. 5,366,490; 5,370,675; 5,385,544; 5,409,453; 5,421,819; 5,435,805; 5,470,308; 5,470,309; 5,484,400; and 5,486,161.
Although the TUNA technique is encouraging in thermal ablation procedures, particularly, in the thermal treatment of BPH, there are several disadvantages inherent to these instruments which detract from their usefulness. In particular, the TUNA instruments are generally complex typically incorporating built in optical systems, aspiration systems, etc. . . . In addition, the TUNA instruments incorporate a complex mechanism for advancing and retracting the RF needles within the tissue and relative to the insulating sleeves. As a result, the instruments are relatively expensive to manufacture thereby precluding disposability of the instrument after a minimal number of uses. Moreover, conventional TUNA instruments are generally enlarged by virtue of the various systems incorporated within the instrument, thus, increasing patient trauma and discomfort during use.
Accordingly, the present disclosure is directed to an apparatus for the RF thermal treatment of prostatic tissue. This apparatus is intended for use in conjunction with a conventional cystoscope and incorporates an RF system and associated mechanism that is at least partially positionable within the working channel of the cystoscope. The apparatus, by use in conjunction with a conventional cystoscope, makes use of the existing systems, e.g., optical and illumination, of in a less complex and less expensive RF thermal treatment device. Furthermore, the apparatus may be used in cystoscopes as small as 5 mm in diameter thereby providing a less invasive system for transurethral ablation as compared to the TUNA instruments and technique. In addition, the apparatus incorporates a novel assembly mechanism which permits the user to selectively couple a variety of RF electrode units having different energy transmitting capabilities to the apparatus to accommodate desired operative parameters.
An apparatus for thermal treatment of tissue, includes an outer member having a frame dimensioned for engagement with the hand of a surgeon and an elongated portion connected to the frame and extending distally therefrom. The elongated portion defines a longitudinal axis and has an axial opening. An electromagnetic probe assembly is releasably mounted to the outer member. The electromagnetic probe assembly includes a handle and an electromagnetic probe connected to the handle. The electromagnetic probe is at least partially positionable within the axial opening of the elongated portion and is adapted for reciprocal longitudinal movement therewithin between a non-deployed position and a deployed position. A manually operable release member releasably mounts the electromagnetic probe assembly to the outer member. The release member is dimensioned and positioned for manual manipulation to move between a first position engaging the electromagnetic probe assembly and preventing release thereof from the outer member, and a second position releasing the electromagnetic probe assembly to thereby facilitate assembly and disassembly of the electromagnetic probe assembly with respect to the outer member. The release member is preferably mounted to the frame of the outer member and is rotatable about the longitudinal axis to move between the first and second positions thereof.
The handle of the electromagnetic probe assembly includes a handle extension which is received within the central opening of the release member. The release member is preferably normally biased to the first position thereof.
The release member may define an inner cam surface adjacent the opening. Similarly, the handle extension of the handle defines a corresponding outer cam surface. The outer cam surface cooperates with the inner cam surface upon advancement of the handle extension within the release member to move the release member to the second position thereof.
The handle extension may define an outer rail. The outer rail defines the outer cam surface at its distal end and defines an abutment surface at its proximal end. The abutment surface is dimensioned and configured to engage the release member to prevent removal of the electromagnetic probe assembly from the outer member when the release member is in the first position thereof and the electromagnetic probe is assembled with respect to the outer member. The frame of the outer member includes at least one longitudinal recess dimensioned for reception of the one outer rail to prevent rotational movement of the electromagnetic probe assembly relative to the outer member.
The apparatus may include a ratchet and associated pawl mechanism for permitting controlled incremental movement of the electromagnetic probe assembly toward the deployed position while preventing movement of the electromagnetic probe assembly toward its non-deployed position. A manually engageable release trigger depends from the frame. The release trigger is movable to disengage the ratchet and associated pawl mechanism thereby permitting movement of the electromagnetic probe toward the non-deployed position.
In a preferred embodiment, the electromagnetic probe includes a radio frequency electrode. The electromagnetic probe may define an axial channel for passage of fluids, and at least one opening extends through an outer wall of the probe in fluid communication with the axial channel to permit exit of the fluids therefrom. A source of fluid may be in communication with the axial channel of the electromagnetic probe. The source of fluid may include one of an irrigant fluid or a conductive fluid.